Multi-radio controller and methods for preventing interference between co-located transceivers

ABSTRACT

Embodiments of a multi-radio controller and methods for preventing interference between co-located transceivers are generally described herein. In some embodiments, the multi-radio controller operates within a multi-radio device and is configured to cause a wireless local area network (WLAN) transceiver to transmit a triggering frame after an active period of a wireless wide-area network (WWAN) transceiver. The triggering frame indicates the duration of a transmission opportunity, which may be restricted to the time between active periods of the WWAN. In response to receipt of the triggering frame, the WLAN access point is configured to transmit a downlink data frame within the transmission opportunity.

This application is a continuation of U.S. patent application Ser. No.12/346,453, filed on Dec. 30, 2008, now issued as U.S. Pat. No.8,630,272, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Some embodiments pertain to wireless communications. Some embodimentspertain to wireless devices that include more than one transceiver, suchas a wireless wide area network (WWAN) transceiver and a wireless localarea network (WLAN) transceiver. Some embodiments pertain to preventinginterference between co-located radios on a multi-radio platform.

BACKGROUND

Many wireless devices today include more than one radio transceiver forcommunicating with more than one wireless network, such as a wirelesswide area network and local area network. One issue with thesemulti-transceiver devices is that the communications of one transceivermay interfere with the communications of another transceiver.

Thus, there are general needs for multi-radio devices and methods thathelp reduce and/or eliminate conflicts between the co-locatedtransceivers of a multi-radio device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a multi-radio communication environment including amulti-radio device (MRD) in accordance with some embodiments;

FIG. 2 illustrates communications in a multi-radio communicationenvironment in accordance with some embodiments; and

FIG. 3 is a procedure for receiving downlink data frames on amulti-radio device in accordance with some embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Examples merely typify possible variations.Individual components and functions are optional unless explicitlyrequired, and the sequence of operations may vary. Portions and featuresof some embodiments may be included in, or substituted for, those ofother embodiments. Embodiments set forth in the claims encompass allavailable equivalents of those claims.

FIG. 1 illustrates a multi-radio communication environment including amulti-radio device (MRD) in accordance with some embodiments.Multi-radio communication environment 100 may include MRD 102, wirelesslocal area network (WLAN) access point (AP) 104, and wireless wide-areanetwork (WWAN) base station 106. MRD 102 may include co-located radiotransceivers for communicating with both WLAN AP 104 and WWAN basestation 106. In some embodiments, MRD 102 includes WLAN transceiver 114for communicating with WLAN AP 104 and WWAN transceiver 116 forcommunicating with WWAN base station 106. MRD 102 may also includemulti-radio controller (MRC) 115 to coordinate the activities of WLANtransceiver 114 and WWAN transceiver 116 to, among other things,mitigate and possibly prevent interference between the co-locatedtransceivers 114 and 116. MRD 102 may include other functional elementsnot illustrated.

In some embodiments, WWAN transceiver 116 and WWAN base station 106 maycommunicate downlink and uplink subframes 121 during active periods. Inthese embodiments, MRC 115 may configure WLAN transceiver 114 and WLANAP 104 to communicate between the active periods. In these embodiments,MRC 115 may cause WLAN transceiver 114 to transmit triggering frame 101immediately after an active period of WWAN transceiver 116. Triggeringframe 101 may indicate at least a duration of a transmission opportunity(T_(TXOP)). In response to receipt of the triggering frame, WLAN AP 104may transmit downlink data frame 105 within the transmissionopportunity. In these embodiments, the duration of the transmissionopportunity may be set at triggering frame 101 to allow downlink dataframe 105 to be received by WLAN transceiver 114 between the activeperiods of WWAN transceiver 116. These embodiments are discussed in moredetail below.

In some embodiments, WLAN transceiver 114 may operate in a power-savingdelivery mode and instruct WLAN access point 104 to refrain fromtransmitting downlink data frames to WLAN transceiver 114 unlessrequested by WLAN transceiver 114. WLAN transceiver 114 may also operatein accordance with a reverse direction (RD) protocol, and MRC 115 maycause WLAN transceiver 114 to set a bit in triggering frame 101 toindicate that WLAN transceiver 114 is granting permission to WLAN accesspoint 104 to send data. These embodiments are discussed in more detailbelow.

MRD 102 may be almost any wireless communication device including bothfixed communication stations as well as mobile communication devices.Examples of MRDs 102 may include a desktop, laptop or portable computerwith wireless communication capability, a web tablet, a wireless orcellular telephone, an access point or other device that may receiveand/or transmit information wirelessly. Although the various functionalelements of MRD 102 are illustrated as having several separatefunctional elements, one or more of the functional elements may becombined and may be implemented by combinations of software-configuredelements, such as processing elements including digital signalprocessors (DSPs), and/or other hardware elements. For example, someelements may comprise one or more microprocessors, DSPs,application-specific integrated circuits (ASICs), radio-frequencyintegrated circuits (RFICs) and combinations of various hardware andlogic circuitry for performing at least the functions described herein.In some embodiments, the functional elements of MRD 102 may refer to oneor more processes operating on one or more processing elements.

In some embodiments, WWAN transceiver 116, WLAN transceiver 114 and MRC115 may be provided on a dual-mode wireless card for use in a laptop orpersonal computer. In some embodiments, WWAN transceiver 116, WLANtransceiver 114 and MRC 115 may be provided or fabricated on a singleintegrated circuit.

The term “WWAN” may refer to devices and networks that communicate usinga broadband or wideband wireless access communication technique, such asorthogonal frequency division multiple access (OFDMA), that communicateduring downlink and uplink subframes which may potentially interferewith the spectrum utilized by WLAN transceiver 114, includinginterference due to out-of-band (OOB) emissions. In some embodiments,WWAN transceiver 116 may be a Worldwide Interoperability for MicrowaveAccess (WiMAX) transceiver, and WWAN base station 106 may be a WiMAXbase station configured to communicate in accordance with at least someElectrical and Electronics Engineers (IEEE) 802.16 communicationstandards for wireless metropolitan area networks (WMANs) includingvariations and evolutions thereof, although the scope of the embodimentsis not limited in this respect. For more information with respect to theIEEE 802.16 standards, please refer to “IEEE Standards for InformationTechnology—Telecommunications and Information Exchange between Systems”Metropolitan Area Networks—Specific Requirements—Part 16: “Air Interfacefor Fixed Broadband Wireless Access Systems,” May 2005 and relatedamendments and versions thereof. In some other embodiments, WWANtransceiver 116 and WWAN base station 106 may communicate in accordancewith at the 3rd Generation Partnership Project (3GPP) UniversalTerrestrial Radio Access Network (UTRAN) Long Term Evolution (LTE)communication standards, Release 8, March 2008, including variations andevolutions thereof, although the scope of the embodiments is not limitedin this respect.

WLAN transceiver 114 may be a wireless local area network or a WirelessFidelity (WiFi) transceiver and may communicate with WLAN AP 104 inaccordance with one or more of the IEEE 802.11-2007 and/or IEEE802.11(n) standards and/or proposed specifications. For more informationwith respect to the IEEE 802.11 standards, please refer to “IEEEStandards for Information Technology—Telecommunications and InformationExchange between Systems”—Local Area Networks—Specific Requirements—Part11“Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY),ISO/IEC 8802-11: 1999” and related amendments/versions.

The use of the terms WiFi, WLAN, WiMAX and LTE are not intended torestrict the embodiments to any of the requirements of the standards andspecifications relevant to these technologies unless specificallyclaimed.

In some multiple-input, multiple-output (MIMO) embodiments, WWANtransceiver 116 may use two or more antennas 118 for communications, andWWAN base station 106 may use two or more antennas 120 forcommunications. In some MIMO embodiments, WLAN transceiver 114 may usetwo or more antennas 125, and WLAN AP 104 may use two or more antennas123 for communicating. In these MIMO embodiments, the antennas of asingle transceiver may be effectively separated from each other to takeadvantage of spatial diversity and the different channel characteristicsthat may result between the stations. The antennas may comprise one ormore directional or omnidirectional antennas, including, for example,dipole antennas, monopole antennas, patch antennas, loop antennas,microstrip antennas or other types of antennas suitable for transmissionof RF or microwave signals. In some embodiments, instead of two or moreantennas, a single antenna with multiple apertures may be used. In theseembodiments, each aperture may be considered a separate antenna. In someembodiments, the antennas of a transceiver may be separated by up to1/10 of a wavelength or more.

In some WiMAX embodiments, WWAN base station 106 communicates with WWANtransceiver 116 within OFDMA downlink and uplink subframes 121 duringand the active periods. In these embodiments, the downlink and uplinksubframes are time-division multiplexed using the same set of frequencysub carriers.

In some LTE embodiments, WWAN base station 106 transmits to WWANtransceiver 116 using OFDMA downlink subframes, and WWAN transceiver 116transmits to WWAN base station 106 using a single-carrier multipleaccess uplink. These communications may take place during activeperiods. The downlink subframes and the single-carrier multiple accessuplink may comprise non-interfering frequency subcarriers.

FIG. 2 illustrates communications in a multi-radio communicationenvironment in accordance with some embodiments. WWAN transceiver 116and WWAN base station 106 (FIG. 1) communicate during active periods203. As illustrated in FIG. 2, WWAN transceiver 116 may receive duringactive periods 203 designated by RX1 and may transmit during activeperiods 203 designated by TX1. Active periods 203 may be periodic (e.g.,regularly repeat) having active period duration 213 and an activeinterval period (P) 215. Active period duration 213 may be a burstlength. As illustrated in FIG. 2, active period 203A has active periodstart time 211, active period duration 213, and end time 207.

In accordance with embodiments, to help mitigate interference with WWANcommunications, MRC 115 (FIG. 1) is configured to cause WLAN transceiver114 to transmit triggering frame 201 to WLAN AP 104 immediately afteractive period 203A. Triggering frame 201 may indicate at least duration206 of a transmission opportunity (T_(TXOP)). In response to receipt oftriggering frame 201, WLAN AP 104 may transmit downlink data frame 205within the transmission opportunity. In these embodiments, duration 206of the transmission opportunity is set at triggering frame 201 to allowdownlink data frame 205 to be received between active periods 203.

In these embodiments, MRC 115 (FIG. 1) may determine duration 206 of thetransmission opportunity based on a time between consecutive activeperiods 203 less the length of triggering frame 201. MRC 115 (FIG. 1)may also determine duration 206 of the transmission opportunity fromactive period duration 213 and active interval period 215. In theseembodiments, the time between the consecutive active periods 203 may bethe difference between end time 207 and start time 209 of twoconsecutive active periods 203.

In some embodiments, the duration 206 of the transmission opportunity(t_(TXOP)) may be determined in accordance with the following equation:t _(TXOP)=min(t _(x) −t _(TRIGGER) _(—) _(END), TXOP_(max)).

In this equation, TXOPmax indicates a maximum network transmitopportunity duration allowed by WLAN AP 104, t_(x) may be any value inthe range [t_(TRIGGER) _(—) _(END), t_(START)], t_(START) may refer totriggering frame start time 217, and t_(TRIGGER) _(—) _(END) may referto triggering frame end time 219.

In some embodiments, WLAN transceiver 114 may transmit triggering frame201 when WLAN transceiver 114 is operating in a power-saving deliverymode and when WLAN transceiver 114 wishes to receive downlink data fromWLAN AP 104. During the power-saving delivery mode, WLAN AP 104 mayrefrain from transmitting downlink data frames to WLAN transceiver 114until downlink data is requested by WLAN transceiver 114. In theseembodiments, WLAN transceiver 114 may inform WLAN AP 104 that it isentering a power-saving delivery mode by setting a power saving (PS) bitin a null frame, although the scope of the embodiments is not limited inthis respect. In some embodiments, the power-saving delivery mode may bean unscheduled-automatic power saving delivery (U-APSD) mechanism inaccordance with the IEEE 802.11(n) specifications referenced above,although the scope of the embodiments is not limited in this respect.

In some embodiments, WLAN transceiver 114 and WLAN AP 104 may operate inaccordance with a reverse direction (RD) protocol. In these embodiments,MRC 115 (FIG. 1) may set a Reverse Direction Grant (RDG) “More PPDU” bitof a high-throughput control (HTC) field in a MAC frame (e.g., to one)to indicate that WLAN transceiver 114 is granting permission to WLAN AP104 to send data. In these embodiments, the “More PPDU” bit may be set(e.g., to zero) in downlink data frame 205 transmitted by the WLAN AP104 to indicate that no additional frames will be transmitted by WLAN AP104. In some embodiments, the RD protocol may be in accordance withIEEE. 802.11(n) specifications referenced above, although the scope ofthe embodiments is not limited in this respect.

In these embodiments that operate in accordance with an RD protocol,once WLAN transceiver 114 has obtained a transmission opportunity, itmay grant permission to WLAN AP 104 to send information back during thetransmission opportunity. In some of these embodiments, the RD initiator(e.g., WLAN transceiver 114) may send permission to the RD responder(e.g., WLAN AP 104) using a RDG in the RDG/More PPDU bit of the HTCfield in the MAC frame. In these embodiments, the “More PPDU” bit may beset to one in triggering frame 201 to indicate that it is grantingpermission to WLAN AP 104 to send data. In these embodiments, the “MorePPDU” bit may be set to zero in downlink data frame 205 transmitted byWLAN AP 104 to indicate that no more frames will be transmitted by WLANAP 104. Without the implementation of an RD protocol, the initiatingstation would have to capture and reserve time on a contention-based RFmedium for each unidirectional data transfer, making it difficult toavoid conflicts with communications of the WWAN transceiver 116 duringactive periods 203.

Through a combination of a power-saving delivery mechanism, such asU-APSD, and an RD protocol, down-link traffic for a WLAN transceiver maybe controlled to help assure that the WLAN transceiver operates betweenactive periods 203 of a co-located WWAN transceiver, thus preventingpotential interference between the WLAN and the WWAN.

In some embodiments, prior to transmission of downlink data frame 205,WLAN AP 104 may transmit a block-acknowledge (BA) 224 to acknowledgereceipt of triggering frame 201. In this situation, the More PPDU bitmay be set to indicate that an additional frame (i.e., downlink dataframe 205) will follow BA 224. As illustrated in FIG. 2, WLANtransceiver 114 may transmit BA 222 to acknowledge receipt of downlinkdata frame 205. In these embodiments, by restricting the length of thetransmission opportunity, downlink data frame 205, BA 224 and BA 222,including triggering frame 201, may fit within the time between activeperiods 203.

In some embodiments, triggering frame 201 may comprise either a dataframe, such as a MAC layer Quality-of-Service (QOS) data frame, or anull frame, and downlink data frame 205 may comprise a QOS data frame,although the scope of the embodiments is not limited in this respect. Insome embodiments, a duration/ID field of the MAC header of triggeringframe 201, in accordance with the IEEE 802.11 specifications, may beused to indicate the duration of the transmit opportunity, although thescope of the embodiments is not limited in this respect.

In some embodiments, a method for receiving downlink data frames from aWLAN AP is provided. In these embodiments, MRC 115 (FIG. 1) may beconfigured to determine duration 213 and period 215 of active period 203from co-located WWAN transceiver 116 and calculate duration 206 of atransmission opportunity. MRC 115 (FIG. 1) may also be configured toinstruct WLAN transceiver 114 to transmit triggering frame 201immediately after active period 203 and indicate duration 206 of thetransmission opportunity within triggering frame 201. These embodimentsare discussed in more detail below.

FIG. 3 is a procedure for receiving downlink data frames on amulti-radio device in accordance with some embodiments. Procedure 300may be performed by a multi-radio controller of a wireless communicationdevice that included co-located transceivers, such as WLAN transceiver114 and WWAN transceiver 116.

In operation 302, the multi-radio controller determines whether or notthe WLAN transceiver is in a power-saving delivery mode. When the WLANtransceiver is not in power-saving delivery mode, additional operationsof procedure 300 are not performed and operation 302 is repeated untilthe WLAN transceiver enters a power-saving delivery mode. When the WLANtransceiver is in a power-saving delivery mode, operation 304 through310 may be performed.

In operation 304, the multi-radio controller determines whether or notthe WLAN transceiver desires to receive downlink data from the WLAN AP.When the WLAN transceiver desires to receive downlink data from the WLANaccess point, operation 306 is performed. If the WLAN transceiverdesires to receive downlink data from the WLAN access point, operation306 may continue to be performed until the WLAN transceiver desires toreceive downlink data from the WLAN access point.

In operation 306, the multi-radio controller determines the duration andperiod of WWAN active periods, such as active periods 203 (FIG. 2).

In operation 308, the multi-radio controller calculates a transmissionopportunity duration, such as duration 206 (FIG. 1).

In operation 310, the multi-radio controller instructs the WLANtransceiver, such as WLAN transceiver 114, to send a triggering frame toindicate the transmission opportunity duration and to grant permissionto the WLAN AP to send data. In these embodiments, the triggering framemay have the RDG “More PPDU” bit set to grant permission to send data.

Although the individual operations of procedure 300 are illustrated anddescribed as separate operations, one or more of the individualoperations may be performed concurrently, and nothing requires that theoperations be performed in the order illustrated.

Unless specifically stated otherwise, terms such as “processing,”“computing,” “calculating,” “determining,” “displaying,” or the like,may refer to an action and/or process of one or more processing orcomputing systems or similar devices that may manipulate and transformdata represented as physical (e.g., electronic) quantities within aprocessing system's registers and memory into other data similarlyrepresented as physical quantities within the processing system'sregisters or memories, or other such information storage, transmissionor display devices. Furthermore, as used herein, a computing deviceincludes one or more processing elements coupled with computer-readablememory that may be volatile or non-volatile memory or a combinationthereof.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable medium, which may be read andexecuted by at least one processor to perform the operations describedherein. A computer-readable medium may include any tangible medium forstoring or transmitting information in a form readable by a machine(e.g., a computer). For example, a computer-readable medium may includeread-only memory (ROM), random-access memory (RAM), magnetic diskstorage media, optical storage media, flash-memory devices, and others.

The Abstract is provided to comply with 37 C.F.R. Section 1.72(b)requiring an abstract that will allow the reader to ascertain the natureand gist of the technical disclosure. It is submitted with theunderstanding that it will not be used to limit or interpret the scopeor meaning of the claims. The following claims are hereby incorporatedinto the detailed description, with each claim standing on its own as aseparate embodiment.

What is claimed is:
 1. User Equipment (UE) comprising: a multi-radiocontroller for controlling a Wi-Fi transceiver and a LTE transceiver,the multi-radio controller configured to: determine a duration of atransmission opportunity (TXOP) based on an active period interval ofthe LTE transceiver; configure a triggering frame to indicate that theWi-Fi transceiver is granting permission to an access point to send datain accordance with a reverse direction (RD) protocol, the triggeringframe to indicate at least a duration of the TXOP; and transmit thetriggering frame within the TXOP immediately after an active period ofthe LTE transceiver, wherein the duration of he TXOP is determined priorto configuration and transmission of the triggering frame.
 2. The UE ofclaim 1 wherein to configure the triggering frame, the multi-radiocontroller is arranged to set a Reverse Direction Grant (RDG) More PPDUbit of a control field in the triggering frame.
 3. The UE of claim 2wherein the multi-radio controller is arranged to configure the Wi-Fitransceiver to operate in a power-saving delivery (PSD) mode during theactive period of the LTE transceiver.
 4. The UE of claim 3 wherein aspart of PSD mode, the multi-radio controller is arranged to configurethe Wi-Fi transceiver to set a power saving (PS) bit in a null frame fortransmission to the access point to indicate to the access point thatthe Wi-Fi transceiver is operating in the PSD mode, and wherein duringPSI) mode, the access point is to refrain from transmitting downlinkdata frames to the Wi-Fi transceiver unless requested by the Wi-Fitransceiver.
 5. The UE of claim 3 wherein the multi-radio controller isarranged to cause the Wi-Fi transceiver to obtain the TXOP, the TXOP tooccur during a transmission and reception free period betweenconsecutive active periods of the LTE transceiver.
 6. The UE of claim 5wherein during the active period of the LTE transceiver, the LTEtransceiver is arranged to transmit and/or receive.
 7. The UE of claim 6wherein the multi-radio controller is arranged to cause the Wi-Fitransceiver to receive a downlink data frame that is transmitted by theaccess point within the TXOP in response to receipt of the triggeringframe.
 8. The UE of claim 7 wherein the multi-radio controller isarranged to cause the Wi-Fi transceiver to receive a block-acknowledge(BA) from the access point to acknowledge receipt of the triggeringframe, the BA to be received prior to the downlink data frame, andwherein the RDG More PPDU bit, when set, indicates that an additionalframe will follow the BA, the additional frame being the downlink dataframe.
 9. The UE of claim 3 wherein the Wi-Fi transceiver and LTEtransceiver are part of a physical layer of the UE and are coupled withtwo or more antennas configured for multiple-input multiple-output(MIMO) communications.
 10. The UE of claim 9 wherein the LTE transceiveris configured for orthogonal frequency division multiple access (OFDMA)communications with an enhanced Node B (eNB) during active periods ofthe active period intervals, and wherein the Wi-Fi transceiver isconfigured for orthogonal frequency division multiplexed (OFDM)communications with the access point in accordance with acontention-based multiple-access technique.
 11. A method performed byuser equipment (UE) for controlling a Wi-Fi transceiver and a LTEtransceiver, the method comprising: determining a duration of atransmission opportunity (TXOP) based on an active period interval ofthe LTE transceiver; configuring a triggering frame to indicate that theWi-Fi transceiver is granting permission to an access point to send datain accordance with a reverse direction (RD) protocol, the triggeringframe to indicate at least a duration of the TXOP; and transmitting thetriggering frame within the TXOP immediately after an active period ofthe LTE transceiver, wherein the duration of the TXOP is determinedprior to configuration and transmission of the triggering frame.
 12. Themethod of claim 11 wherein to configure the triggering frame, the methodcomprises setting a Reverse Direction Grant (RDG) More PPDU bit of acontrol field in the triggering frame.
 13. The method of claim 12wherein the method comprises configuring the Wi-Fi transceiver tooperate in a power-saving delivery (PSD) mode during the active periodof the LTE transceiver.
 14. The method of claim 13 wherein as part ofPSD mode, the method comprises configuring the Wi-Fi transceiver to seta power saving (PS) bit in a null frame for transmission to the accesspoint to indicate to the access point that the Wi-Fi transceiver isoperating in the PSD mode, and wherein during PSD mode, the access pointis to refrain from transmitting downlink data frames to the Wi-Fitransceiver unless requested by the Wi-Fi transceiver.
 15. The method ofclaim 13 wherein the method comprises configuring the Wi-Fi transceiverto obtain the TXOP, the TXOP to occur during a transmission andreception free period between consecutive active periods of the LTEtransceiver.
 16. The method of claim 15 wherein during the active periodof the LTE transceiver, the LTE transceiver is arranged to transmitand/or receive.
 17. The method of claim 16 wherein the method comprisesconfiguring the Wi-Fi transceiver to receive a downlink data frame thatis transmitted by the access point within the TXOP in response toreceipt of the triggering frame.
 18. The method of claim 17 wherein themethod comprises configuring the Wi-Fi transceiver to receive ablock-acknowledge (BA) from the access point to acknowledge receipt ofthe triggering frame, the BA to be received prior to the downlink dataframe, and wherein the RDG More PPDU bit, when set, indicates that anadditional frame will follow the BA, the additional frame being thedownlink data frame.
 19. The method of claim 13 wherein the Wi-Fitransceiver and LTE transceiver are part of a physical layer of the UEand are coupled with two or more antennas configured for multiple-inputmultiple-output (MIMO) communications.
 20. The method of claim 19wherein the LTE transceiver is configured for orthogonal frequencydivision multiple access (OFDMA) communications with an enhanced Node B(eNB) during active periods of the active period intervals, and whereinthe Wi-Fi transceiver is configured for orthogonal frequency divisionmultiplexed (OFDM) communications with the access point in accordancewith a contention-based multiple-access technique.
 21. A non-transitorycomputer-readable storage medium that stores instructions for executionby one or more processors to perform operations for controlling amulti-radio controller of user equipment (UE) having a Wi-Fi transceiverand a LTE transceiver, the operations to configure the UE to: determinea duration of a transmission opportunity (TXOP) based on an activeperiod interval of the LTE transceiver; configure a triggering frame toindicate that the Wi-Fi transceiver is granting permission to an accesspoint to send data in accordance with a reverse direction (RD) protocol,the triggering frame to indicate at least a duration of the TXOP; andtransmit the triggering frame within the TXOP immediately after anactive period of the LTE transceiver, wherein the duration of the TXOPis determined prior to configuration and transmission of the triggeringframe.
 22. The non-transitory computer-readable storage medium of claim21 wherein to configure the triggering frame, the multi-radio controlleris arranged to set a Reverse Direction Grant (RDG) More PPDU bit of acontrol field in the triggering frame, wherein the multi-radiocontroller is arranged to configure the Wi-Fi transceiver to operate ina power-saving delivery (PSD) mode during the active period of the LTEtransceiver, wherein as part of PSD mode, the multi-radio controller isarranged to configure the Wi-Fi transceiver to set a power saving (PS)bit in a null frame for transmission to the access point to indicate tothe access point that the Wi-Fi transceiver is operating in the PSDmode, wherein during PSD mode, the access point is to refrain fromtransmitting downlink data frames to the Wi-Fi transceiver unlessrequested by the Wi-Fi transceiver, and wherein the multi-radiocontroller is arranged to cause the Wi-Fi transceiver to obtain theTXOP, the TXOP to occur during a transmission and reception free periodbetween consecutive active periods of the LTE transceiver.